Rotary knife



April 4, 1939.

' ROTARY KNIFE Filed Aug. 16, 1935 2 Sheets-Sheet 1 J r INVENTOR.

v QualazreQ. Qlazyar G. A. UNGAR; 2,153,013

BY W ATTORNEY.

; April 4, 1939. G. A. UNGAR 2,153,013

ROTARY KNIFE Filed Aug. 16, 1935 ZSheets-Sheet 2 INVENTOR; 1

' Qua-fave Q. 2059a? Patented Apr.4,1939 p I 2,153,013

" UNITED'STATES PATENT orrlcr.

ROTARY KNIFE Gustave A. Ungar, Pelham Manor, N. Y., assignor to S & S Corrugated Paper Machinery 60., Inc., Brooklyn, N. Y., a corporation of New York Application August 16, 1935, Serial No. 36,519 9 Claims. (Cl. 164-436) My invention relates to a novel cutting mechmade for cutting the sheets at right angles to the anism and more particularly to novel revolving direction of travel of the sheet. or rotary shears for cutting a continuous web or In order to have the sheet cut-off at right sheet fed at a constant speed. angles to the sheet travel, it is necessary to mount Revolving knives or rotary shear blades which the axes of the revolving blade holders at an out while the sheets are fed through at constant angle (equal to the helix angle of the spiral speed must, in order to cut straight across edges blades). This necessitates arranging-the driving a and uniform sheets, fulfill the following requiremechanism at an angle to the feeding mechanism, ments. i. e., none of the drive shafts excepting the shafts 10 (a) The horizontal velocity components of the for the feed rolls can be parallel with the frame 10 moving shear blades, while cutting takes place, of the machine.

must be equal to the horizontal sheet velocity, My invention contemplates a novel construcin order to prevent tearing, or buckling of the tion of knives that eliminates all these difliculties. sheet. Accordingly objects of my invention are to (b) The cutting of the sheet must take place provide, substantially straight shear blades; plane 15 gradually, so as to prevent excessive strains on shear blade supportin Surfaces on the revolving the shearing mechanism, as well as excessive lad supp a s of t blade s pp t in a power consumption. plane at right angles to the direction of the It will be clear that the first of these is essensheet travel.

m tial to prevent tearing or buckling, since the There are other objects of my inventien which horizontal component of the shears is the forward to ether with the foregoing w app in t speed at the point of cutting. If this is les tha detailed description which is to follow in conthe speed at which the paper is moving, it; will nection with the drawings in which, cause buckling of the paper-if more it ill cause Figure 1 shows the elevation of a shear frame tearing. looking toward the frame in the direction of the 25 The second requirement is desirable in order to S et t ve avoid excessive peak loads. If the cutting time Figure 2 is a Side elevation- .could be distributed uniformly over the entire Figure 3 s a vertical c n through 3-- of cycle of the knife drum, then obviously less power re would be required than the other xtr me s Figure 4 is a diagrammatic view of four points 30 in which the entire cut is a single instantaneous f the Shears evenly Spaced along the Sheet operation in which all the work of cutting must Width, together With a Projected Side View of the be accomplished in an instant. It is accordingly cuttingcedge of the upper shear. desirable to approach the former condition as F ure 5 sh ws a d a m p n w of nearly as: possible. the line of tool travel for generating the cutting 35 In order to accomplish this the shear blades e shave in the past been arranged spirally with the Figure 6 is a d a m sho e v oc t shearing edge displaced along a cylindrical surcomponen of t e f e a in p s o t face. shear.

40 While such blades can be made to fulfill the Re e sp fic y to Figure 4 I have shown 40 i 'above requirements, they present several prosections of the upper and lower shear blades as nounced disadvantages. they engage with each other from theleft edge Because of the necessary spiral shape the of the sheet (looking toward the machine) to manufacturing cost of the revolving blade supt e right edge w th h e v y Spaced te ports, as well as of the blades is high, and remediate 'posltions. While the sheet is being cut, 45

placement costs of shear blades are therefore the angular velocity of shear blades around their also high. Shear blades are frequently made in axes is constant; 5 repre the angle of the\ sections, to overcome thedimculty of heatshear blade travel while the sheet travels the treating long spiral shear blades. This ,of course distance a. 60 results in interruptions of the cutting edge. If this distance a is divided for instance into But if the cutting period is to occur over a .four equal parts a/4, the corresponding positions reasonable portion of the drum cycle, it is 010- of shear blade intersections will be found to devivious that the paper will have moved through a ate at the intermediate points from the. corredistance equal to the speed of the paper times sponding angular positions of shear blade cari u the cutting time. Provision must accordingly be rier, when dividing the angle ,6 into 4 equal parts 5/4, the angular velocity and the sheet velocity both being uniform.

At its right edge, the sheet is sheared by the shearing edge In of the upper blade and the shearing edge le of the lower blade. Both edge profiles are assumed to have penetratedto the center of the sheet which has thereby been sheared at this point. The shearing profiles are curved in such a manner that there will be no mutual interference as the blades continue to revolve around their axes.

After the sheet has travelled the distance a/4 the shearing edge profiles which then have penetrated to the center of the sheet at this instant must then be 2 for the upper blade and 2e for the lower blade. At this point one-fourth of the width of the sheet has been sheared. See also Figure 5. g

When thesheet has travelled an additional distance a/4 the then co-acting shear edge profiles are 3 and 3e. One-half of the sheet width has been sheared.

After an additional travel of a/4 of the sheet, the co-acting shear edge profiles are in and 4e. Three-fourths of the sheet .width has been sheared.

When the sheet has travelled the remaining distance a/4, the co-acting shear edge profiles are 5n and 5e, and the full width of the sheet has been sheared.

In every one of the shear edge points indicated as well as in all intermediate points, the sectional profiles (in vertical planes perpendicular to the sheet, and parallel to the sheet travel) of the lower and upper blades respectively are uniform. These profiles can therefore be generated by means of suitable profile tools (milling cutters) travelling at a uniform speed, along straight line L}, 3, 4, 5, in Figure 5, which is the hypotenuse of a right triangle having as the other sides the sheet travel distance a and b, the maximum length of the shear (maximum sheet width) While the generating tool travels along this line, the shear blade carrier is rotated at uniform speed through angle 5. Any suitable mechanism can be employed for feeding the generating tool along line l-5, while the blade carrier revolves through 3. The same tool, carrier actuating mechanism is also used for grinding the shearing edges proper.

Figure 4 also shows diagrammatically the elevation of the cutting edges of both shear blades, lu, Zn, 311', u, 511', and 'e, 2e, 3e, e, 5e, respectively, when these blades are at the beginning of the cut at the left edge of the sheet. A plan View of the upper shear blade, In", 21,",- 3u", In", 5u" also is shown projected at right angle to the elevation of the upper shear edge at the beginning of the cut.

It will be seen from this elevation and projec-- tion, that the shearing edges are not straight lines, but slightly curved. However, the deviation from the straight is so slight that the shear blade can be made from a straight flat piece of tool steel, and therefore the supporting faces of the blade carriers are flat and in planes parallel to the blade carrier axes. The arrangement of the shear blades and their carriers is shown in the Figures 1, 2, and 3. a

B and 6' represent the frames supporting the revolving blade carriers 1 and 8 in bearings 9, III, II, and I2. The shafts-Band I to which the blade carriers I and 8 are'fastened also have fastened thereto the gears 15 and I6 respectively, which keep the blade carriers in correctly timed -.shown in Figure 1.

relation. Blade carrier I has two fiat perpendicular faces I1 and 18 to which is fastened the upper blade l9 by means of screws 20. Blade carrier 8 has two fiat perpendicular faces 2| and 22 to which lower blade 23 is fastened by means of screws 24. These fiat surfaces ll, l8, 2|, and

22 are located in planes parallel to their respec' tive blade carrier axes and are therefore easy to machine. a

The two end profiles of each shear blade as well as the shearing edges 28 and 29 are also Profile 25 corresponds to In in Figure 4 while, 26 corresponds to 511 in Figure 4. Profile 21 corresponds to le in Figure 4, while, 28 corresponds to 5e.

The direction of the sheet travel is indicated by arrows 30; the rotation of the shear blade is indicated by arrow 32. The blades can readily be adjusted for wear by axially shifting the blade along the supporting back edges I8 and 22.

It will be seen from the above that the cutting of the sheet proceeds gradually from edge to edge. The cutting angle can be chosen as very considerable (45 and even more). This angle is limited only by the necessary space requirements so that each shear blade can clear the supporting bar of the other shear blade while revolving past each other.

The correct velocity is constant and indicated by '05. The angular velocity of the shear blades at the pitch line of the timing gears l5 and i6 is also constant and indicated by 'Up whereby 17p 'l)s- The horizontal components of the shear blade velocities are indicated by 'Uh.

As will be seen from the diagram, the tangential blade velocity or at the beginning of the cut (at the left edge of the sheet) is a maximum, but its horizontal component, being the tangential blade velocity in times the cosine of the momentary angle a of the blade position, is substantially identical with the sheet velocity.

As the sheet advances and the cutting progresses, the tangential blade velocity decreases, because of the decrease of the active blade radius, but the momentary blade angle oz',. also decreases and vh' m' cosine 11' remains substantially constant during the entire cutting period.

The shear blade profiles shown in the diagrams 3 and 4 are such as would be particularly suitable for the cutting of cardboard and the like. For sheet metal cutting the shear blade angles would have to be appropriate for metal, i. e. less acute.

For thin sheetsvof paper, Celluloid, rubber, etc., only one of the blades would have a knife like cutting edge, while the other blades would mere- 1y act as a steady rest for the material while the knife cuts through it. The method of generating the profile of the steady rest would be the same as that of the regular shear edges.

Although I have described a preferred embodi-- ment of my invention,-it will be understood that it may take other forms and I do not intend to be limited by these illustrations except as set forth in the appended claims. I v

I claim:

i. In a cutting mechanism for continuous strip material; a blade carrier; a drive for said carrier;

a blade rigidly mounted on said carrier the active knife radius varying continuously from one end to the opposite end in an amount to produce asubstantially constant horizontal component of'the blade velocity at each successive cutting edge as it ing profile so shaped as to cut a straight edge at right angles to the direction of web travel.

2. In a cutting mechanism for continuous strip material; a blade carrier axis; a blade carrier having two surfaces in planes parallel to the blade carrier axis and a blade edge rigidly mounted in said carrier the active knife radius varying continuously from one end to the opposite end in an amount to produce a substantially constant horizontal component of the blade velocity at each successive cutting edge. as it engages the sheet.

3. In a cutting mechanism for continuous strip material; a drum; a blade carrier having two surfaces in planes parallel to the blade carrier axis and a blade edge rigidly mounted in said carrier, the active knife radius varyingcontinuously from one end to the opposite end in an amount to produce a substantially constant horizontal component of the blade velocity at each successive cutting edge as it engages the sheet, and said carrier being mounted at right angles to the direction of travel of theweb material to be cut. v

4. In a cutting mechanism for continuous strip material; a drum;'a blade carrier having two surfaces in planes parallel to the blade carrier axis and a blade edge rigidly mounted in said carrier, the active knife radius varying continuously from one end to the opposite end in an amount to produce a substantially constant horizontal component of the blade velocity at each successive cutting edge as it engages the sheet, and said carrier being mounted at right angles to the direction of travel of the web material to be cut, and the blade edge being shaped so that the web will be cut in a line at right angles to the directions of travel of the web.

5. In a cutting mechanism for continuous strip material; a blade carrier axis; a blade carrier having two surfaces in planes parallel to the blade carrier axis and a blade edge rigidly mounted in said carrier, the active knife radius varying continuously from one end to the opposite end "in an amount to produce a substantially constant horizontal component of the blade velocity at each successive cutting edge as it engages the sheet,

tinuously from one end to the opposite endin' an amount to produce a substantially constant horizontal component of the blade velocity at each successive cuttingedge as it engages the sheet,

and a second blade carrier axis; a blade carrierhaving two surfaces in planes parallel to the blade carrier axis and a blade edge mounted on said second carrier, and said carriers being mounted at right angles to the directions of travel of the web material to be cut.

7. In a cutting mechanism for continuous strip material; a blade carrier axis; a blade carrier having two surfaces in planes parallel to the blade carrier axis and a blade edge rigidly mounted in said carrier, the active knife radius varying continuously from one end to the opposite end in an amount to produce a substantially constant horizontal component of the blade velocity at each successive cutting edge as it engages the sheet, and a second blade carrier axis; a blade carrier having two surfaces in planes parallel to the blade carrier axis and a blade edge mounted on said second carrier, and said carriers being mounted at right angles to the directions of travel of the-web material to be cut, and the blade edges being shaped so that the web will be cut in a line at right angles to the direction of travel. I

8. In a cutting mechanism for continuous strip material; a first and second blade carrier; a drive for said carriers; a blade mounted on each of said carriers; said carriers being mounted at right angles to theadirections of travel of the web material to be cut and said blades having shearing profiles so shaped as to cut a-straight edge at right angles to the direction of web travel; the ends of the blades edges being in a plane with the axis of the carriers, and the blades between the ends forming a slight curve; the intermediate points of the blades deviating sufliciently to permit theshearing edges of both blades, to intercept at progressive points on the web, which for equal rotation oi the blades carriers are spaced equal distances apart.

9. In a cutting mechanism for continuous strip material; a blade carrier; a drive for said carrier; a blade mounted on said drum; said drum being mounted at right angles to the directions of travel of the web material to be out and said blade 

